Detachable bit tool



y 1943- A. WERME 2,318,273

DETACHABLE BIT TOOL Filed May 28, 1 1.942

k N100 v s Patented ay 4, 1943 DETACHABLE BIT TOOL Adolph Wermc, Worcester, Mass, assignorto Reed & Prince Manufacturing Company, Worcester, Mass, a corporation of Massachusetts Application May 28, 1942, Serial No. 444,803

6 Claims.

The present invention relates to a tool comprising a bit element and more particularly to means for attaching the bit element to the shank of the tool and for detaching ittherei'rom.

It is an object of the invention to provide improved means for attaching, detaching and interchanging bit elements, thus making possible the use of various types of bits with a single tool and facilitating replacement or repair of worn or broken bits. Another object of the invention is to provide a means of attachment which is simple, cheap, easy tooperate and adapted to resist accidental disengagement.

The nature of the invention and its objects will be more fully understood from the following description of the drawing and discussion relating thereto.

In the accompanying drawing:

Fig. 1 is a view in side elevation illustrating the attaching means of the invention applied to a hand tool;

Fig. 2 is an enlarged view in elevation and partial cross section, showing the attaching means:

Fig. 3 is a cross section taken on the line 33 of Fig. 2; and

Fig. 4 is a cross section taken on the line 4-4 of Fig. 2.

The invention includes a bit element and sleeve means for attaching and holding the bit element on a shank member. Among other features, there is provided a helical slot which cooperates with the sleeve means to facilitate attachment and removal of the bit element and to prevent accidental disengagement.

Referring more in detail to the drawing, Fig. 1 illustrates a hand tool such as a screw driver or the like with the bit element detached. Numeral i denotes a handle to which is fixed a shank 2 supported by a ferrule 3. The extremity of the shank 2 is cut away to provide a slabbed end 4 (Fig. 2). The slabbed end may for example be formed by making a cut in a direction axially of the shank and a second cut at right angles to the axis of the shank, the second cut intersecting the upper end of the first cut. There is thus obtained a flat side 5 extending generally axially of the shank, and a second fiat side 6 extending in a direction at right angles to the axis of the shank.

Located in spaced relation to the slabbed end 4 is an annular groove 1 (Fig. 2) extending around the outer periphery of the shank. Rotatably mounted about the shank 2 is a sleeve 8 which is provided with projections 9 extending inwardly from the inner periphery of the sleeve into the annular groove I. The projections 9 are adapted to move freely in the groove I and thereby to permit the sleeve to be rotated about the shank while at the same time preventing removal of the sleeve from the shank.

The length of the sleeve 8 is such that it projects beyond the slabbed end 4 of the shank. The projecting end of the sleeve and the slabbed end of the shank thereby combine to provide a brace-like member in which the bit element may be secured and supported.

Numeral l0 refers to a bit element which in the specific form shown is provided with screw driver blades ll of some suitable form such as that shown in the drawing, which is suitable for driving sc-called recessed head screws. The opposite end of the screw driver bit element is cut away to provide a slabbed end I2 which matches with the slabbed end 4 of the shank 2. This slabbed end portion of the screw driver bit element presents a flat side l6 (Fig. 1) and a second flat side I3 having axially extending edges l4 and I5.

In spaced relation to the slabbed end l2 of the bit element is an annular slot l1 extending around the peripheral surface of the bit. Connecting with the annular slot I1 is a helical slot l8 which extends axially of the bit to a point at which it intersects the fiat side l6 between the edges I4 and I5, a may be observed from an inspection of Fig. 1. In the specific form shown, the helical slot l8 extends around a part only of the outer periphery of the bit element within a peripheral area corresponding to that defined by the edges l4 and 15 of the flat side l3.

Numeral l9 indicates a projection from the inner periphery of the sleeve 8 at a point such that the projection or stud may project into the annular slot 11 when the bit element is in a completely engaged position with respect to the shank (Fig. 2); Since the helical slot l8 intersects the annular slot II, the projection or stud l9 may. in one position, be moved into the helical slot by withdrawing the bit element, and at the same time rotating the sleeve 8. The correct position of the sleeve, with respect to the bit element, for removing the latter, may be indicated by a dot or mark 20 formed on the bit and a similar dot or mark 2| formed on the outer periphery of the sleeve 8.- When the marks are aligned, the bit may be withdrawn.

In assembling the bit element, the slabbed end I2 is entered through the sleeve 8 and allowed to extend for a short distance into the space between the slabbed end I of the shank and the inner periphery of the sleeve. At this point the projection I! will be accommodated in the space facing the flat side I 3 or the bit 10. While the bit element isin this intermediate position, the sleeve 8 is rotated into a position in which the projection l9 becomes aligned with the inner extremity oi the helical slot i8. The bit element is then advanced into the sleeve 8, the sleeve being simultaneously rotated in a counter-clockwise direction as viewed in Fig. 3.

At the point where the slabbed ends 4 and [2, of the shank and bit element respectively, become completely locked against one another, rotation of the sleeve 8 passes the stud or projection is from the helical slot 18 into the annular slot i1. Further rotation carries the stud out oi! alignment with the end of the helical slot, which effectually locks the bit element in a fully engaged position with respect to the shank.

In order for the bit element to be removed, it is' then necessary for the projection IS on the sleeve 8 to be rotated into alignment with the end of the helical slot I81 on the bit element, when the bit element may be pulled outwardly and the sleeve 8 rotated in a clockwise direction as viewed in Fig. 3.

The helical formation of the slot l8 prevents th bit element from becoming readily detached in case the projection l9 becomes accidentally aligned with the end of the slot I8. This is an important aspect of the invention since the detachable bit element cannot be easily displaced or lost and can only be released by a positive rotation of the sleeve in a clockwise direction.

It is pointed out that the slabbed end construction of the bit element is especially adapted to the use of a projection or stud on the inside of the sleeve 8. When the slabbed end is first inserted in the sleeve 8, there remains a space which allows the stud to project inwardly from the sleeve and to be engaged in the helical slot I 8. In the usual use of the tool, it will be observed that the shank and bit elements, while locked together, are free to turn together within the sleeve 8. The sleeve is preferably formed with an outer knurled surface 22. The knurled surface furnishes a convenient gripping surface for turning the sleeve or holding the working end of the tool while it is being used. Attention is also directed to the fact that the sleeve may be employed as a grip for holding the screw driver bit element in engagement with the head of a screw without interfering with or being subject to the rotation of the shank and the bit element. This provides for greater ease of operation.

It may be desired to employ modifications in connection with any of the elements disclosed. For example, the matching slabbed ends of the shank and bit'element may be of different forms, and other types of locking means may be employed in conjunction with the sleeve member. I may desire to employ the detachable bit element in connection with power-driven tools. Other types of bits may be used. It may also be found desirable to employ a rotatable sleeve in combination with a, screw driver independently of the detachable bit element described.

While I have shown a preferred embodiment of my invention, it should be understood that various other changes and modifications may be resorted to, without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. An article of the character described comprising a shank, a sleeve rotatably mounted about the shank and projecting beyond its extremity to provide a receptacle, 8. bit element mounted in the receptacle, means for engaging the bit element in fixed relation with respect to the shank, said bit element having an annular groove formed therearound and a helical groove connecting with the annular groove locking means on the inner periphery of the sleeve and normally engaged in the said annular groove, saidlocking means in one position of the sleeve being adapted to pass from the annular groove into the helical groove to permit removal of the bit element from the shank.

2. An article of the character described including a shank, a sleeve rotatably mounted on the shank and projecting beyond the end thereof, a bit element mounted in the sleeve, said bit element provided with a flat side portion adapted to be engaged in fixed relation to the shank, the said flat side portion presenting edges which extend in a direction generally axially 01' the bit element, the bit element being formed with an annular groove occurring in spaced relation to the flat side portion and being further formed with a helical groove, said helical groove extending between the annular groove and the fiat side and terminating at a point between the said axial edges of the flat side and facing said flat side, and locking means in the sleeve arranged to move in the said grooves.

3. An article of the character described including a shank, a sleeve rotatably mounted on the shank and projecting beyond the extremity thereof, a bit element mounted in the sleeve, said bit element provided with a fiat side portion engaged in fixed relation with the shank, the said flat side portion presenting edges which extend in a direction generally axially of the bit element, the bit element being formed with an annular slot occurring in spaced relation to the flat side I portion, and a helical slot which extends between the annular slot and the fiat side portion, the helical slot connecting with the annular slot at a point substantially in alignment with one of the said edges of the flat side portion and terminating at a point adjacent the other of the said edges of the fiat side portion, and locking means in the sleeve for engaging in the slots.

4. An article of the character described comprising a shank having a slabbed end portion, said shank formed with an annular groove occurring in spaced relation to the slabbed end portion, a sleeve rotatably mounted on the shank, a projection in the sleeve and extending into the annular groove for securing the sleeve on the shank, a bit element supported in the sleeve and formed with a slabbed end which matches the slabbed end of the shank, said bit element having an annular slot formed about its periphery, and a helical slot extending between the said annular slot and the slabbed end portion of the bit and locking means mounted inside the said sleeve, said locking means being arranged to pass along the helical slot as the sleeve is rotated to provide for attaching or removing the bit element.

5. An article of the character described, comprising a shank, a sleeve rotatably mounted about the shank, a bit element mounted in the sleeve in fixed relation to the shank, said bit element having an annular slotv and a helical slot connecting with the annular slot, and locking means in the sleeve arranged to move through the helical slot to detach the bit element from the shank.

6. An article of the character described comprising a shank. a bit element, a rotatable sleeve in part surrounding each 0! said shank and said bit element, and means for eng ging the bit element in fixed relation with respect to the shank, said means comprising a helical groove connecting with an annular groove and locking means normally engaged in the said annular groove, said locking meansin one position ofthe sleeve being adapted to pass from the annular groove into the helical groove to permit removal of the bit ele- 5 meat from the shank.

ADOLPH WERME. 

